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This booklet has been written by the Autonomic Unit at The National Hospital for Neurology and Neurosurgery (NHNN). The aim of the booklet is to provide information about the 24- hour ambulatory blood pressure and heart rate (24-hr BP) monitor.

It is intended for use by patients (or their families or carers) who have been referred to our service for a 24-hr BP monitor. If you have any questions about this, a member of the Autonomic team will be happy to answer them for you.

The Autonomic Nervous System (ANS) is an important mechanism that controls all the bodily functions that we have unconscious control of. This includes things like heart rate, blood pressure, temperature control, the bladder, digestion and bowel movements.

When one or more parts of this system are impaired, it can result in a variety of disorders. In the Autonomic Unit, we focus on testing how well the ANS is functioning in a patient, using various tests, to be able to diagnose these conditions.

This monitor measures your BP and HR over a 24-hour period while going about your normal day. You will be asked to perform some activities throughout the day which will challenge your BP and HR.

The data that is recorded on the monitor is analysed by the autonomic unit and will be useful information for your consultant to have to help with diagnosing medical conditions or planning and carrying out treatments.

A 24-hr BP monitor is a useful diagnostic test, although any clinical benefit should always outweigh the possible risks associated with the procedure.

You may experience a sore arm with light bruising if you have fluctuating blood pressure as the cuff can squeeze uncomfortably tight. This may affect your ability to sleep as you would normally.

You may experience irritation or chafing from the cuff. The cuff can be adjusted to make it more comfortable.

It is important to be aware that some of the activities you are asked to do may trigger your symptoms.

The decision to have a 24-hr BP monitor is entirely yours. Declining this procedure will not affect our attitude towards you or influence any other aspect of your care. It may mean, however, that your consultant cannot be as certain or specific about any future treatment or diagnosis.

Your consultant or clinical nurse specialist (CNS) will have taken into account the potential risks and benefits of having a 24-hr BP monitor during your initial referral. There may be some alternative methods available under certain circumstances, although the possibility of these should be discussed with your referring doctor or CNS.

The clinical autonomic scientist (CAS) or associate CAS fitting your monitor will need access to your bare upper arm so please wear suitable clothing.

Ensure that your schedule for the next 24 hours will be compatible with the test requirements (refer to ‘The testing procedure’ within the accordion titled 'What happens during a 24-hr BP monitor?' below).

You may need to stop certain medications prior to testing, although the consultant or CNS should be able to advise you during your initial consultation; if you are unsure, please call us directly or ask us when you confirm your appointment.

We want to involve you in all the decisions about your care and treatment. If you decide to go ahead with treatment, by law we must ask for your consent. This confirms that you agree to have the procedure and understand what it involves.

If you are unsure about any aspect of your proposed treatment, please do not hesitate to speak with a senior member of staff again.

The testing procedure

The CAS or associate CAS will require access to your non- dominant upper arm to fit the blood pressure cuff. The cuff is attached to a monitor that is 12cm x 9cm x 3cm and fairly light. The monitor can be worn on a belt round your waist or on a sling over your shoulder. This must be worn for a continuous period of 24 hours.

Your BP will be taken every 20 minutes during the day and hourly overnight. During this time, you will be asked to perform a number of activities and to keep a diary of BP recording timings and symptoms. These activities include things like mild exertion and postural challenges. We will also ask for recordings before and after meals.

You will be able to remove the cuff for showering during the 24- hour period if required.

The monitor must be returned after 24 hours or over/after the weekend for Friday appointments. The monitor must be returned at the time arranged as it will be required for another patient.

It will take around 30 minutes to fit the monitor, explain how to use it and how to keep the diary.


Once you have completed all of your clinical tests with us, the results will be analysed and discussed at a multi-disciplinary team (MDT) meeting.

A brief summary letter will then be sent to you and your referring doctor (normally your GP) detailing the results of your tests.

You will then be contacted by one of our consultants or CNS for a follow-up appointment to explain the results in more detail, and to also answer any questions you may have.

You may find the following websites useful:

UCLH cannot accept responsibility for information provided by other organisations.


National Hospital of Neurology and Neurosurgery

The Autonomic Unit

2nd Floor Queen Mary Wing

Queen Square

London WC1N 3BG


Direct tel: 0203 448 3079

Switchboard: 0203 456 7890

Fax: 0203 448 3878



The Autonomic Unit is located on the second floor of the Queen Mary Wing at the National Hospital for Neurology & Neurosurgery, Queen Square.

Please follow signs from the main entrance towards the Queen Mary Wing and you should find the appropriate set of lifts/stairs on your right-hand side. Head to the second floor and use the intercom to contact our admin team who will let you in once you have confirmed your identity.

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Page last updated: 01 May 2024

Review due: 30 November 2025